248 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



the lagoons of Saxony at the middle of the Permian 

 epoch. Still more recently Thevenin has described 

 in the upper Coal formation of Commentry a genus 

 Sauravus, which seems properly to belong to the 

 same group, and whose very perfect ossification of 

 the skeleton implies the existence of numerous 

 precursors at still earlier epochs. In the course 

 of late years, Amalitzky has discovered in the 

 Permian of the banks of the river Dwina terrestrial 

 Reptiles far advanced in evolution, and belonging 

 to the three great groups of the Pareiasaurians, 

 the Dicynodonts, and the Dinosaurs. We can 

 distinguish a time approaching when the kingdom 

 of Reptiles will stretch over a large part of Primary 

 times. Every now and then some sensational 

 discovery brings us unexpected revelations on 

 the antiquity of groups. Thus Vidal suddenly dis- 

 covered in the lithographic limestone of the upper 

 Jurassic of Catalonia, a Palceobatrachus, a real 

 anuric Batrachian, of which the existence as a 

 group appeared to go back hardly to the beginning 

 of the Oligocene. Similarly, the highly specialized 

 type of the Turtles had for a long time no known 

 representative further back than the upper Jurassic 

 of Soleure, where Riitimeyer made known a great 

 number of species, with marine habitat, appertaining 

 to the two sub-orders of the Pleurodera and the 

 Cryptodera. The differentiation of these two 

 groups as early as the end of the Jurassic, of itself 

 showed us the great antiquity of the Chelonian 

 type ; in fact, Quenstedt was not long in dis- 

 covering in the sandstone of the upper Trias of 

 Suabia a Pleuroderous Turtle, the Proganochelys, 



